I will try to explain...
we have 2 servers: server1 and server2. Both servers are running Windows 2003 and are added to a clusterserver named server3.
The server is configured active-passive, which means that from the outside the user always looks and connects to shares available on the "virtual" server server3.
But in fact that virtual server3 is physically server1 or server2. Which server depents on where the cluster resources are active. It could be either server1 or server2 and also in the meantime you can do a failover between the two nodes. Still the user will always looks at server3.
If server2 fails and the virtual server3 was connected to server2 it will automatically fail-over to node1, which is in this case server1.
For the end-user nothing changes. They will always connect to server3 !!
That is a virtual node and the shares on that node are virtual shares !! Connecting to a physical share on lets say server1 or server2 is not a problem from DOS, but connecting to a share on server3, the virtual node, is a problem from within DOS
Understand now ?
If not I will explain more